Properties of 13052Te 78 as observed in the 40 min β-decay of 130Sb

Abstract

Gamma-ray and conversion electron spectra associated with the decay of 40 min 130Sb have been measured with Ge(Li) and Si(Li) detectors. The antimony samples were produced using the on-line isotope separator OSIRIS to isolate the fission products from 235U. On the basis of the measured singles and γ-γ coincidence spectra, a new level scheme has been constructed. The most important states observed are: 839.4 keV, 2 +; 1632.8 keV, 4 +; 1815.1 keV, 6 +; 2100.8 keV, 5 −; and 2146.0 keV, 7 −. Using delayed coincidence techniques a half-life of 9.8±0.5 ns was deduced for the 6 + state. This implies that the 182.3 keV transition connecting the 6 + and 4 + states has B(E2) exp = 240±12 e 2 · fm 4. This value is 2.8 times greater than that theoretically predicted if both states are assumed to be pure (g 7 2 ) 2 two-proton configurations. The T 1 2 . for the 7 − state was determined to be 115±8 ns giving a hindrance factor of 1.8 × 10 7 with respect to the Weisskopf estimate for the 330.9 keV 7 − → 6 + El transition. The origins of the 5 − and 7 − states are ascribed mainly to the ( 1 h 11 2 ), 3 s 1 2 ) and ( 1 h 11 2 , 2 d 3 2 ) two-neutron configurations, respectively.